Other Hormones Are Produced In The Ovaries. First There Is Oestrogen, Produced By The Follicles As They Develop During The First Half Of The Monthly Cycle. It Is The Build-Up Of Oestrogen In The Woman’s System That Triggers The Surge Of Luteinising Hormone. Oestrogen Stimulates The Development Of The Lining Of The Womb, Or Endometrium, In Preparation For A Possible Pregnancy. It Also Makes The Cervical Mucus Become Thin And Runny To Allow The Sperm Through To Reach The Egg. Second, There Is Progesterone Which Is Produced During The Second Half Of The Monthly Cycle By The Corpus Luteum Left In The Ovary Once The Egg Has Been Released. This Makes The Lining Of The Womb Receptive For Implantation Of The Embryo In The Womb And Supports The Pregnancy. It Also Makes The Cervical Mucus Turn Thick To Act As A Barrier To Either Sperm Or Infection.
Finally, Once The Embryo Has Reached The Womb, It Produces A Hormone, Human Chorionic Gonadotropin. This Encourages The Corpus Luteum To Continue Producting Pgogesterone Which In Turn Supports The Developing Pregnancy. So It Is A Circular System Each Part Mutually Aiding The Other In An Ultimate Goal Of Achieving And Maintaing A Pregnancy.
The Quality As Well As The Quantity Of A Woman’s Egg Seems To Diminish As She Grows Older. This Deteriotation Is Thought To Be One Of The Reasons Why Older Women Are More Likely To Have A Baby With A Severe Genetic Disability. By The Time They Reach Their Mid 40s Most Women Will Have Used Up All Their Eggs And Will Stop Ovulating . However , They May Continue To Menstruate For Several Years After Ovulation Has Ended, Until The Hormonal System Changes And There Is No Longer The Monthly Build-Up Of The Lining Of The Womb. This Process, The Menopause, Marks A Natural End To The Woman’s Reproductive Life. 
